I was in the same dilemma last month, minus the Wii, because I'd rather nail my dick to a burning wall than own a console called "wii", and settled on a 360 over a PS3, because of the games. The 360 just has better games. There are no RPGs I know of on the PS3 at all. Full stop. Zero. 360 has Lost Odyssey, which is a 360 exclusive. I have high hopes for Mistwalker, because they've got Hironobu Sakaguchi. I expect them to be the next Squaresoft. Not Square-Enix, but Squaresoft, as they were before they started gasping out their dying breath. I haven't tried Blue Dragon, but I've heard good things about it. Mobile Ops: One Year War is also slated to be a 360 exclusive. Lost Odyssey and Mobile Ops alone were enough to justify the cost of the 360 as far as I'm concerned, and they're the only games I was concerned with when I made my purchase. Since then, I've had tons of fun with Dynasty Warriors: Gundam, but I've been meaning to try the Dynasty Warriors franchise since I got my PS2 last year, so I can't really credit the 360 for introducing me to it.

EDIT: Also, achievements rock.